Compressed gas actuated circuit breaker



May 19, 1970 J. VAITINS 3,513,276 v COMPRESSEDGAS ACTUATED CIRCUIT BREAKER Filed April 4. 1967 1 NVENTOR. Jams V1ms United States Patent 3,513,276 COMPRESSED GAS ACTUATED CIRCUIT BREAKER Janis Vitins, Wettingen, Switzerland, assignor to Aktien- US. Cl. 200-148 1 Claim ABSTRACT OF THE DISCLOSURE A gas blast switch includes a switch chamber which is continuously filled with pressurized gas by way of a replenishment pipe line from a pressurized gas storage tank. Inside of the switch chamber are located a pair of separable contacts, at least one of which is hollow and a blast valve which when opened for a brief period at the same time as the contacts separate serves to discharge the gas from the switching point through the hollow contact to atmosphere. An annular flow duct surrounding the blast valve leads in the pressurized gas from an inlet located at the side of the switch chamber and is provided with means for steadying the gas flow before it combines with the other gas already in the switch chamber.

The present invention relates to a gas e.g. air blast switch, the switch chamber of which is continuously filled with compressed gas and which is in continuous communication with a compressed gas-storage tank over a replenishment line terminating in the proximity of the switching section, the brief discharge of the quenching gas being effected over at least one hollow contact during the opening of the switch.

Gas blast switches are known whose contacts are hollow and arranged inside a switching chamber and which are filled both in the open, and in the closed position of the contacts with compressed gas. In these switches an exhaust valve is opened approximately simultaneously as the contacts move apart during the opening of the circuit so that a gas flow is produced which is used to quench the arc formed on the switching section. The exhaust valve is kept open only for a short time. The short open time of the valve is due to the fact that there is a sufficient recovery of the switching section against the return voltage, in addition to a positive quenching of the are. With a small volume of the switch chamber, the pressure reduces during the quenching process to such a degree, however, that replenishment of the compressed gas becomes indispensable while the arc quenching process is still being carried on. To this end, the switch chamber is placed in constant, i.e. continuous communication with the compressed gas-storage tank by a replenishment line. As soon as there is a pressure difference in the switch chamber relative to the storage tank, replenishment of the compressed gas sets in. If the replenishment line opens into the switch chamber in the proximity of the switching section, which is practically always the case if care is taken that the switch chamber is kept within reasonable limits in its dimensions, the outflowing gas mixes with the incoming gas current from the replenishment line, which results in vortices in the range of the switching section, which can have a harmful effect on the recovery of the switching section and lead to so-called late arc-backs.

In order to avoid these inconveniences, and to increase the switchable voltage in such a switch chamber, it is suggested according to the invention that the replenishrnent line pass over on the side of the switch chamber into a flow duct in which means are provided for steadying the gas flow. This way the incoming gas is first steadied before it combines with the gas current which is fed to the switching section.

The accompanying drawing illustrates one embodiment of the invention, the single view presented being a central longitudinal section through the gas blast switch.

With reference now to the drawing, in the switch chamber 1, constantly filled with compressed gas, is arranged the stationary and hollow contact 2 which carries a sealing gasket 3 with which cooperates the tubular, moving blast valve element 4 in closing position. Inside the blast valve element 4 is arranged a cylindrical array of finger contacts 5 moving with the valve. These contacts 5, which form a movable bridge, are connected in closed position of the contact 2, with the likewise stationary nozzle tube 6. The represented position, however, shows the moment when .the blast valve is open and the switching section interrupted. The compressed gas flows, as indicated by arrows, from the switch chamber 1 through the two nozzle tubes 2, 6 into the open air. In the illustrated embodiment, this switch chamber 1, is connected over a replenishment line 12 with a compressed air-storage tank (not represented). The end of the replenishment line at the side of the switch chamber is designated with 7, and passes over into an annular flow duct 8 surrounding the cylinder 13 in which the annular blast valve 4 slides. In the latter are arranged a perforated disk 9 and several steadying lattices 10 by which the incoming gas is steadied. Besides, a fine screen is secured on the perforated disk, which keeps off even the finest particles. A flow constricting bulge 11 which is made preferably of insulating material, and arranged in the proximity of the switching section, sees to it that the gas flow duct leading radially inward from the lattices to the switching section becomes constantly narrower. The arrangement has the eflfect that the replenishing current of gas is first steadied before it arrives in the switching section. In this Way, the improved arrangement has the advantage that the switchable voltage of the switch chamber is considerably increased while, at the same time, late arc-backs, i.e. re-ignitions of the switching section after several hundredths of a second, are avoided.

Moreover, while the inventive concept has been illustrated with a switch construction where both switch contacts are hollow and serve to discharge gas from the switch chamber to atmosphere, the inventive concept can be applied equally as well to a switch construction em ploying only one hollow contact to carry the discharge gases through the gas blast valve to atmosphere.

I claim:

1. In an electrical switch of the gas blast type, the combination comprising a switch chamber which is maintained in a constantly gas-pressurized state, a pair of switch contacts located within said switch chamber, at least one of said switch contacts being stationary and hollow to permit gas fiow therethrough, an annular blast valve surrounding said stationary hollow contact, said blast valve being slidable within a cylinder and being movable between a closed state in which said switch contacts are closed and an open state in which said switch contacts are open and gas is discharged from said switch chamber into the gas entrance end of said stationary hollow contact for flow therethrough, an annular gas replenishment duct surrounding said cylinder, a gas replenishment pipe line in constant sommunication with a supply source of pressurized gas and which is connected with the inlet end of said annular duct for delivering pressurized gas thereto from said supply source, the gas outlet end from said annular duct terminating in a constricting bulge for progressively narrowing the cross section of the gas flow path at its discharge end and directing the gas radially inward toward the gas entrance end of said hollow contact and means including a perforated disc and a plurality of lattices located downstream from said disc in said annular duct for steadying the gas flow therethrough and effecting a reduction in turbulence in the region where the replenishment gas issuing from said nuclear duct meets the replenishment gas issuing from said annular duct meets the gas being discharged from said switch chamber into said stationary hollow contact during a contact opening operation.

References Cited UNITED STATES PATENTS 2,382,850 8/ 1945 Bennett.

3,240,910 3/ 1966 Floessel.

3,396,253 8/ 1968 Schubert et a1. 200-448 FOREIGN PATENTS 1,297,821 5/ 1962 France.

1,202,380 10/ 1965 Germany.

ROBERT S. MACON, Primary Examiner 

